Currently, under the circumstances where the global environmental issues are greatly highlighted, reduction of carbon dioxide gas emission has been demanded in order to prevent global warming. For example, automobiles with gasoline engines which are major emission sources of the carbon dioxide gas have begun to be replaced with alternatives such as hybrid electric vehicles and electric vehicles. Typical large secondary batteries as power sources for hybrid electric vehicles and electric vehicles need to have high output and a large capacity. Therefore, the storage buttery module constituting this is generally composed of a plurality of battery cells configured by series-parallel connections.
As the secondary battery of large capacity, lithium-ion batteries are widely known. The handling of the lithium-ion battery needs a measure to prevent a high voltage charge and performance degradation due to over-discharge. Therefore, the storage battery module mounted on a hybrid electric vehicle or an electric vehicle and configured by using a lithium-ion battery as each battery cell, generally, has a function of monitoring the battery conditions, such as a voltage, current, temperature for each battery cell.
As an apparatus for monitoring the state of each battery cell as described above, for example, a state monitoring device disclosed in PTL 1 listed below is known. A wireless tag of the electromagnetic induction type is provided in a module for measuring the voltage value of each battery cell, and the state monitoring device transmits a voltage value of each battery cell to a reader by a wireless signal using the wireless tag. Thereby, the cost of wiring and insulation is reduced.
Further, PTL 2 discloses a storage battery control system which has a plurality of battery packs in which a plurality of slave unit controllers are connected to a master unit controller. In the storage battery control system, when a failure occurs in the master unit controller and the communication between the master unit controller and the slave unit controller becomes impossible, the slave unit controller connects and communicates with a master unit controller of another battery pack. Thus the situation in which the control of the storage battery by the slave unit controller becomes impossible is prevented.